doCreateDirectory respects ServerSideEncryption
Added support for a ClientConfiguration in FileSystemOptions

* This allows setting some flexiblity when creating the AmazonS3Client
* The default ClientConfiguration returned is slightly different
  from Amazon's default values and increases the maxErrorRetries to
  8 from 3 (a much more sane value in almost all cases, since
  S3 operations tend to fail often).
Time to migrate on 7 :)
Update ignore file for direnv
Release 2.2.0
Prepare for next release cycle
Add S3 bucket prefix as environment variable
Add test for loading list of children
Merge pull request #1 from abashev/branch-2.2.x

Pull in latest changes from master